Bulletin 25 2010 - BSES

12
QCrOps / peTer sAMsON, keiTh ChANDLer, NADer sALLAM
We demonstrated at Tully that zero-
or zonal-tillage planting preserves
Metarhizium spores in the cane row – the
best position to come into contact with
future generations of canegrubs. In an
old ratoon where Metarhizium had been
infecting greyback canegrubs, most spores
were under stools in the row, with fewer
on the side of the row and very few in the
interspace – see figure 1.
With zero tillage and a double-disc
opener planter or with zonal tillage (rotary
+ ripper/grubber + rotary in 76 cm band)
and a conventional planter, planting back
into the old rows, the Metarhizium spores
in the new cane crop remained in the best
position to contact future generations of
canegrubs. figure 2 shows results for the
zonal-tillage option.
iNseCTiCiDes
We tested two questions about canegrub
control with insecticide applied when
using double-disc opener planters or in
dual rows, relative to their registrations
for conventional planters and single rows.
The questions were:
Spores/g OD soil (x 10 3 )
50
40
30
20
10
0
OlD RATOON
0 mm 250 mm 500 mm 750 mm
Lateral position
• Should application rates be increased
for dual rows? (There are about 11,100
metres of crop-row per hectare for
dual rows with 1.8 m between beds,
compared with 6,700 row metres for
single rows at 1.5 m spacing.)
• Are the narrow row-bands of
insecticide from double-disc opener
planters as effective as wider bands
that are obtained when using
conventional planters?
fIGuRE 1 | Numbers of Metarhizium spores in an old ratoon crop,
from the centre of the row (0 mm) to the centre of the interspace (750
mm); note that most spores were in the row – where canegrubs live.
[‘New farming systems’
should encompass not only
sustainable agronomic practices but
also sustainable pest management
with more precisely targeted
pesticide application than has been
the rule.]
Effective application rates of insecticides
suSCon Blue, suSCon Maxi and Confidor
Guard in dual rows were within the range
currently on the registered labels: the
high end of current label rates per 100 m
of single row was effective when applied
as the same amount per 100 m of dual-
row bed.
Both suSCon Blue and suSCon Maxi gave
satisfactory control of greyback canegrub
when applied in narrow bands between
the discs of a double-disc opener planter
– comparable to control in conventional
furrow-width bands.
Spores/g OD soil (x 10 3 )
50
40
30
20
10
0
Control of greyback and Childers
canegrubs with suSCon Maxi was also
satisfactory when applied at fill-in of
conventional planting furrows in a dualrow
configuration.
Confidor Guard (liquid imidacloprid) gave
at least 1-year control of greyback and
Childers canegrubs in dual rows when
applied either at planting or at fill-in.
Confidor Guard was effective when applied
using coulters in dual-row ratoons (for
greyback and southern 1-year canegrubs)
and in dual-row plant cane (for greyback
canegrub). When applying Confidor Guard
in dual rows against greyback canegrub,
twin coulters were slightly more effective
than a single coulter.
use patterns in new farming systems
differ from label recommendations in
conventional systems. Despite the fact
that application rates are comparable,
recommendations to industry cannot be
made until the Australian Pesticides and
Veterinary Medicines Authority (APVMA)
approves the changes.
ZONAl TIllAGE,
CONVENTIONAl PlANTER
Row Shoulder Interrow
0-150 mm 150-300 mm
fIGuRE 2 | Numbers of Metarhizium spores with a zonaltillage
system at two depths; spore distribution in the new crop
(1st ratoon) was similar to the old crop cycle.